Cooling system for rear-end power plants



June 8, 1954 R. DAFOE 2,680,490 COOLING SYSTEM FOR REAR-END POWER PLANTS Filed Oct. 5, 1950 3 Sheets$heet l June 8, 1954 COOLING SYSTEM FOR REAR-END POWER PLANTS Filed 0ct. 3, 1950 3 Sheets-Sheet 2 L. DAFOE 2,680,490

June 8, 1954 R. DAFOE coounc SYSTEM FOR REAR-END POWER PLANTS Filed Oct. 5, 1950 3 Sheets-Sheet 3 9N W /M\ i it v I. E x, m 5. mm n NM Q i 11? m N E V w.

Patented June 8, 1954 UNITED STATES PTENT OFFICE 2,680,490 COOLING SYSTEM FOR REAR-END POWER PLANTS Leslie R. Dafoe, Seattl worth Motor Truck Corporation,

Washington a corporation of e, Wash, assignor to Ken- Seattle, Wash.,

Application October 3, 1950, Serial No. 188,259

Claims.

the engine compartment of a pressure condition high by comparison with outplant for the bus.

3 and 4 are fragmentary longitudinal Figs. vertical sectional views jacketed engine 22 which serves as the power Both the engine and the fan is provided a belt 23 working through a small opening w ch is cut in the intervening longitudinal wall section it of the angular partition.

The other and transverse wall section it of said partition has a comparatively large opening therein, and fitted in this opening to o cupy a position immediately to the front of the fan is a radiator 24 to which is attached a shroud 25 for directing the fan-blown column of air through the core. Associated with the radiator and mounted upon that side of the core which is exposed to the alley i! there is provided a set of shutters 2B pivotally mounted for opening and closing movements and activated in any desired manner, preferably by means of a piston working in an air cylinder and giving reciprocal movement to a sliding bar which connects through crank arms with the several shutters. The large majority of trucks, and busses in particular, include as their accessory equipment an enginedriving air compressor for the brake system, and hence it becomes desirable to employ pressure air as the instrumentality for operating the radiator shutters.

It is common practice to have the radiator shutters open and close in concert with the opening and closing of a thermostat which opens the engine jackets for circulation of water pumped through the radiator system. To avoid dust, for reasons which will be hereinafter expressly pointed out, t s is objectionable in the instance of a rear-end engine, and it is a feature of the present invention that the valve which controls the operation of the shutters, while it is made automatically responsive to temperature conditions within the water-circulating system, operates by a condition differing from that which opens the water jackets. To this end I employ two separate thermostats. One said thermostat, hereinafter referred to as the Toy-pass thermostat, is contained within a pipe section El and is the usual thermostat acting by its closing to trap engine water against circulation through the radiator. This thermostat commonly is set to open at 175 a temperature condition approximating the loW point of the engines efficiency range. The other said thermostat, and which I will hereinafter refer to as a shutterstat, is designated by 23 and lies beyond the pipe section 2": in a connecting pipe as leading to the upper end of the radiator. As applied to a set of shutters activated by pressure air, a suitable shutterstat for my purpose is one associated with a control valve governing the movement of pressure air through two pipes 31 and 3% connecting with the air cylinder for the shutters. Beyond the necessary characteristic of being set to open at a temperature well below that of the bypass thermostat, say a temperature 25 lower, the structural nature of the shutterstat is, however, unimportant.

The pressure column of air drawn by the suction of the fan through the roof opening it and blown through the core of the radiator into the engine compartment is discharged through two openings, as 33 and 3t, each fitted with a grill and located one in the outer wall of the alley ll and the other in the oppositely disposed outer wall I of the engine chamber it. There is also provided at the rear of the bus a hinged door 35 giving access to both the engine chamber and the fan chamber and arranged, when closed, to tightly seal the interior of the rear-end compartment against liability of the rather heavily laden air which swirls up from the rear wheels seeping into the compartment.

From the foregoing description it will be ap parent that the zone from which I draw air into the fan chamber is comparatively free of dust and as long as the shutters remain open this air column is blown into the alley and thence moves in opposite directions to spill out the two side openings 33 and 34. In prior arrangements, the shutters have been made responsive to the engine thermostat wherefor the same close as the temperature of the water drops below the efficiency range. Such a drop in temperature will perforce occur whenever the engine is relieved of its load while the bus is under way as, for example, when running down hill, and it therefor follows that a shutter, when controlled by a thermostat set to close at the low point of the efficiency range, will be closed at frequent intervals during the normal running of the bus. When so closed, and as distinguished from the high pressure condition de veloped within the engine compartment when the fan is blowing air through the same, there obtains a low-pressure condition and it is this low-pressure condition which permits road dust to enter the compartment through the discharge opening. The degree to which the discharge opening sucks dust-laden air depends in large extent upon the design of the compartment, and particularly the location of the discharge opening. The perfected design of the present invention is quite advantageous in this respect in that two discharge openings located opposite one another in the side walls of the bus minimize suctional pull within the compartment but there still remains a sunlcient pull to draw some dust if the shutters are closed. My employment of a shutterstat separate and apart from the engine thermostat and set to close at F. assures, during the hot seasons when dust is a problem, an open condition of the shutters at very nearly all times while the vehicle is under way. While the engine is being warmed up preparatory to starting a run, and also during winter months, there is no problem insofar as dust is concerned.

The structural design of the system as a whole, the arrangement of its parts, and the manner of their working are believed clear from the foregoing detailed description having express reference to my now preferred embodiment. Some changes in the details of construction may be re sorted to without departing from the spirit of the invention and I accordingly intend that the hereto annexed claims be given a breadth in their interpretation fully commensurate with the broadest scope to which the employed language admits.

What I claim is:

l. In a bus, a body presenting a compartment at the rear divided by a partition into two separated chambers with an opening being provided in the partition to establish con munication between the two chambers, and having a tunnel for incoming air leading into one of said chambers, the other said chamber extending the full width of the body and having openings for the discharge of air provided in each of the opposite side walls, a water-jacketed engine housed in said full-width chamber and serving as the power plant for the bus, an engine-driven fan housed in the other chamber and operating to draw air from the tunnel and force the same through said communication opening into the engine chamber, a radiator for the engine having its core overlying said communication opening, said radiator being fitted with shutters. acting by an opening thereof to establish communication between the two chambers and by a closing thereof to shut in the partition to establish communication beoff one from the other said chamber, and means tween the two chambers, and having a tunnel interconnected with the shutters for controlling for incoming air leading into one of said chamthe opening and closing of said shutters bers from a roof opening exposed to the outside 2 The structure of claim 1 having means by 5 atmosphere, the other chamber having a wall which the radiator and the jackets of the enopening likewise exposed to the outside atmosgine are brought into water-circulating connecphere for discharge of air, a water-jacketed ention only as the engine heat reaches a given eifiine ng a the D Plant for the bus d operates automatically in response to the tempositioned to locate its core in overlying relation somewhat lower than the low point of said efiithrough the engine Jackets to and from the radiciency range. ator only when the temperature condition of the 3. In a bus, a body presenting a compartment engine is within a predetermined range of effiat the rear divided by a partition into two sepacient operati n, n n ine-driven fan housed in rated chambers with an opening being provided the first-named chamber for forcing air from in the partition to establish communication bethe tunnel through the core of the radiator leading into one of said chambers from a roof ator core, means for opening and closing said of air provided in each of the opposite side walls, under a condition of engine heat approximately a water-jacketed engine housed in said full-width 25 F. lower than the low point of said efiiciency chamber and serving as the power plant for range.

the bus, an engine-driven fan housed in the other 7. In a bus, a body presenting a compartment chamber and operating to draw air from the at the rear extending the full width of the body tunnel and force the same through said communiand having a rear corner portion set apart from cation opening into the engine chamber, and a e ba ance of the compartm t by an an ular connection only as the engine heat reaches a he compartment givin acc s to both th fan are made to open under a condition of engine the chambers, a radiator having water-circuheat approximately 25 below the low point of lating connection with the jackets of the engine said efiiciency range. and mounted to have its core overlie said com- 4. The structure of claim 3 in which said means munication opening, an air tunnel leading into brings the radiator and the jackets of the engine the fan chamber from a roof opening exposed into water-circulating connection only as the ento the outside atmosphere, and air-discharge gine heat reaches an approximate 175 F. tem- Openin in ach of the pp t de Walls of perature, and wherein the thermostatically conthe engine chamber likewise exposed to the outtrolled shutters are made to open under a conside atmosphere.

dition of engine heat approximating 150. 8. In a bus, a body presenting a compartment 5. In a vehicle having separate engine and at the rear extending the full width of the body tion opening and providing an air-admission the balance of the compartment by n angular engine compartment, a water-cooling radiator connection with the jackets of the engine and having its core overlying said communication mounted to have its core overlie said communicathe engine thermostatically controlled to permit chamber from an opening exposed to the outwater to circulate from the radiator through the side atmosphere, and an air-discharge opening jackets of the engine only when the temperafrom said main portion of the compartment liketure condition of the engine is above the low wise exposed to the outside atmosphere. point of a given efliciency range, a shutter for 9. In a bus, a body presenting a compartment the core of the radiator, and means controlled at the rear divided by a separating partition into shutters to close only when the temperature of establish communication between the two chamof the eficiency range. respective opening one for admission of air to 6. In a bus, a body presenting a compartment the fan chamber and the other for the disat the rear iv d d y a pa t nt tWO s pacharge of air from the engine chamber, a waterrated chambers with an opening being provided jacket engine housed in said engine chamber and serving as the power plant for the bus, an enginedriven fan housed in the fan chamber and operating to draw air from the air-admission opening and force the same through said communication opening into the engine chamber, and a radiator for the engine having its core overlying said communication opening, means being provided by which the radiator and the jackets of the engine are brought into water-circulating connection only as the engine heat reaches a given efiiciency range, said radiator being fitted with thermostatically controlled shutters which are made to open under a condition of engine heat approximating 25 below the low point of said efficiency range.

10. In a vehicle having an engine compartment providing openings for the admission thereto and the discharge therefrom of a column of cooling air, a water-jacketed engine serving as the power plant for the vehicle and housed in the engine compartment, a water-cooling radiator having its core overlying said admission opening, a normally open shutter for the admission opening, a power-driven fan operativeiy associated with the radiator and acting when the shutter is in said normal open condition to cause a pressure column of air to pass through the engine compartment entering through said admission opening and leaving through said discharge opening, connections between the radiator and the engine governed by a thermostatic control so as to permit water to circulate from the radiator through the jackets of the engine only when the temperature condition of the engine is above the low point of a given efficiency range, and namely a range in which the engine is intended to function under normal operating conditions when the same is powering the vehicle, and means controlled thermostatically by means independent of said first-named thermostatic control to cause the shutter to close only when the temperature of the engine drops somewhat below said low point of the efiiciency range.

References Gited in the file of this patent UNITED STATES PATENTS 

